<!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="UTF-8" />
        <meta http-equiv="X-UA-Compatible" content="IE=edge" />
        <meta name="viewport" content="width=device-width, initial-scale=1.0" />
        <title>Document</title>
        <style>
            .box {
                width: 100px;
                height: 100px;
                border: 1px solid red;
            }
        </style>
    </head>
    <body>
        <button id="btn">改变颜色</button>
        <div id="box" class="box"></div>
        <script>
            let btu = document.getElementById("btn");
            let box = document.getElementById("box");
            function randoms(max, min) {
                return parseInt(Math.random() * (max - min + 1) + min);
            }
            btu.onclick = function () {
                box.setAttribute(
                    "style",
                    `background-color:rgba(${randoms(255, 1)},${randoms(
                        255,
                        1
                    )},${randoms(255, 1)})`
                );
            };
        </script>
    </body>
</html>
